The manipulation and process of a microscopic object has been especially focused on recently relative to nanotechnology and biotechnology. The microscopic object of the order of micrometers can be manipulated under a microscope by a laser beam without being touched by use of a laser tweezers, and it can be processed by laser ablation and a polymerization reaction of the laser. However, it is difficult to bring the microscopic object and another object together or to inject another object into the microscopic object even by combining the above techniques. Since a shock wave (laser-induced shock wave) generated by focusing the laser beam in a liquid by an objective lens of a microscope can highly accelerate the object, it is regarded as effective energy to perform an operation requiring high energy.
Here, techniques regarding the above are disclosed in Japanese Unexamined Patent Publication No. 2003-210159, Japanese Unexamined Patent Publication No. 2003-344260, Japanese Unexamined Patent Publication No. 2005-144538, Japanese Unexamined Patent Publication No. 2005-335020, Japanese Unexamined Patent Publication No. 2005-287419, Japanese Unexamined Patent Publication No. 2005-168495, and Appl. Phys. Lett., 84, 2940 (2004), Appl. Phys. A, 79, 795 (2004).
While a method of accelerating particles in a uniform solution to form a concentration difference includes an electrophoresis method and an dielectrophoresis method, only ion having a charge can be migrated in the electrophoresis method. According to the above electrophoresis method, since a migration speed is low, the problem is that it takes time for analysis. In addition, chromatography using absorption and permeation or distribution equilibrium is a method of migrating an object to form a concentration difference and this method is widely used as a separation and analysis method of a mixture. Meanwhile, an ultracentrifugal separation method is applied to a high molecular weight molecule and used to measure and separate the molecules. However, since both of them include diffusion and migration of the object in principle, it is difficult to implement both high resolution and high speed or miniaturization.
More specifically, according to the conventional electrophoresis method and the dielectrophoresis method, the problem is that the target is limited to the ion having the charge and the migration speed is low. In addition, according to the conventional chromatography and the centrifugal separation method, the problem is that it is difficult to implement both high resolution and high speed or miniaturization.
Here, many researchers generate shock waves by focusing the pulse laser into the liquid with the microscope, and study its generation mechanism (Appl. Phys. Lett., 84, 2940 (2004), Appl. Phys. A, 79, 795 (2004)). The well known techniques using the laser-induced shock wave include separation of a cell and a part of the cell (Japanese Unexamined Patent Publication No. 2003-210159), acceleration and migration of particles (Appl. Phys. A, 79, 795 (2004)), control of a particle traveling direction (Japanese Unexamined Patent Publication No. 2003-344260), and process of a microscopic object (Japanese Unexamined Patent Publication No. 2005-144538 and Japanese Unexamined Patent Publication No. 2005-335020). The accelerated particle includes a particle such as a gold colloid and a high molecular latex particle having a size of order of nanometers to micrometers, and a live cell. Thus, by use of the acceleration of the particles, marking is performed with the intention of enhanced Raman spectroscopy in the cell by the injection into the cell under the microscope. According to the present invention, it has been found that the target to be accelerated can range from a low molecule to a high molecule, so that a function depending on the molecule can be applied and a molecular size can be analyzed. In addition, a laser injection method for injecting an extracellular object into a cell with the laser-induced shock wave is proposed (in Japanese Unexamined Patent Publication No. 2005-287419, and Japanese Unexamined Patent Publication No. 2005-168495).
Thus, according to the above Japanese Unexamined Patent Publication No. 2003-210159, Japanese Unexamined Patent Publication No. 2003-344260, Japanese Unexamined Patent Publication No. 2005-144538, Japanese Unexamined Patent Publication No. 2005-335020, Japanese Unexamined Patent Publication No. 2005-287419, Japanese Unexamined Patent Publication No. 2005-168495, and Appl. Phys. Lett., 84, 2940 (2004), Appl. Phys. A, 79, 795 (2004), they are techniques related to the process and the cell injection limited to the specific particle and cell, and cannot cope with the case where the first and second particles having the different diameters exist in the dispersion liquid.